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luks like E to me....here are my 2 cents....if the number is divisible by 36,,it shud be divisible by both 9 and 4for a number to b divisible by 9,, the sum if digits shud be divisible by 9for a nummber to b divisible by 4 the last two digits shud be divisible by 4

If a and b are single digits from 0 to 9, inclusive, what is the value
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Updated on: 28 Jul 2017, 08:40

Bunuel wrote:

If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.(2) The number a1b is divisible by 4.

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1 Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

Evaluating statement 1:From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36,

Now combining the divisibility by 4 and 9 to find divisibility by 36, b is inconclusive as 72 and 76 are divisible by 4Also by extension, a has dual values (2 and 7) that make 2+a+5+7+2 = 18 or 2+a+5+7+6 = 27 divisible by 9

Thus, statement 1 is also insufficient and the answer is E.[/b]

Originally posted by rulingbear on 28 Jul 2017, 08:05.
Last edited by rulingbear on 28 Jul 2017, 08:40, edited 2 times in total.

Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 08:10

1

rulingbear wrote:

Bunuel wrote:

If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.(2) The number a1b is divisible by 4.

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1 Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36, b is clearly 2, i.e last 2 digits cannot be 76.Now we need to find a, here by approximation the first # of the quotient is 7, i.e 36(8-1) = 288-36= 252Hence a is clearly 2, as any other number would spill over and would make 25a7b indivisible by 36. Thus, 1 is sufficient and the answer is A.

in the number 25776, the last two digits are 76,,, and the number is very much divisible by 36...

Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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28 Jul 2017, 08:15

mohshu wrote:

rulingbear wrote:

Bunuel wrote:

If a and b are single digits from 0 to 9, inclusive, what is the value of (a + b)?

(1) The number 25a7b is divisible by 36.(2) The number a1b is divisible by 4.

IMO, it helps to start from statement 2 as it's much simpler and may give hints to evaluate statement 1 Statement 2 is insufficient using the divisibility rule by 4 i.e b is either 2 or 6 and a could be any number.

From statement 2 we know that b is either 2 or 6 since it's divisible by 25a7b is divisible by 36, b is clearly 2, i.e last 2 digits cannot be 76.Now we need to find a, here by approximation the first # of the quotient is 7, i.e 36(8-1) = 288-36= 252Hence a is clearly 2, as any other number would spill over and would make 25a7b indivisible by 36. Thus, 1 is sufficient and the answer is A.

in the number 25776, the last two digits are 76,,, and the number is very much divisible by 36...

Re: If a and b are single digits from 0 to 9, inclusive, what is the value
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20 Sep 2018, 04:14

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